A conventional pressure valve is applied in various water supply devices, such as conventional or digital showering systems, as disclosed in U.S. Pat. No. 8,267,111 B2, US Publication Nos. US 2013/0042923 A1 and US 2012/0138177.
The water supply device is normally a temperature control faucet and includes a thermostatic valve and a temperature sensing element for matching with the thermostatic valve; the thermostatic valve can adjust desired mixing ratio of cold water and hot water based on a preset showing temperature.
The thermostatic valve can adjust the desired mixing ratio of the cold water and the hot water by adjusting a size of each of a cold-water orifice and a hot-water orifice. However, when the cold-water pressure of the cold-water orifice and the hot-water pressure of the hot-water orifice are not equal, the desired mixing ratio of the cold water and the hot water cannot be adjusted precisely. To overcome such a problem, a pressure balance valve is fixed on an inlet end of the water supply device so as to automatically adjust water pressures of the cold water and the hot water, thus balancing the cold-water pressure of the cold-water orifice and the hot-water pressure of the hot-water orifice.
Conventional pressure balance contains a housing, a fitting sleeve disposed in the housing, and a valve core, wherein between the housing and the fitting sleeve is defined a receiving chamber so that the valve core axially slides in the receiving chamber. The valve core includes a cold-water pressure room and a hot-water pressure room which are spaced from each other by a pressure sensing fence, and the pressure sensing fence has a cold-water detection face and a hot-water detection face so that the cold-water pressure in the cold-water pressure room and the hot-water pressure in the hot-water pressure room act on the cold-water detection face and the hot-water detection face, when a pressure difference between the cold-water pressure and the hot-water pressure is sensed, the valve core acts on the pressure sensing fence and automatically slides so as to balance the cold-water pressure and the hot-water pressure.
A receiving chamber of a pressure balance valve of another temperature control faucet is defined by a part of components of a thermostatic valve, such as, a thermostatic valve core in a cylinder shape, an end plug mounted on one first end of the thermostatic valve core, and a central shaft fixed on a second end of the thermostatic valve core. The central shaft drives the thermostatic valve core rotates in a valve seat of the thermostatic valve so as to adjust a mixing ratio of cold water and hot water, such that a peripheral fence of the receiving chamber can be rotated as well during mixing the cold water and the hot water together.
Accordingly, the valve core of the pressure balance valve has to axially slide quickly and accurately according to the pressure difference of the cold-water pressure and the hot-water pressure, hence a high stability and precision of the pressure balance valve is required.
Likewise, in some conditions, the valve core has to stop the cold water flowing into the cold-water pressure room or to stop the hot water flowing into the hot-water pressure room, a high tightness between the valve core and the housing is therefore required as well. To comply with above-mentioned requirements, a gap between an outer surface of the valve core and an inner surface of the housing has to be less than 0.03 mm, and the outer surface of the valve core and the inner surface of the housing have to be machined smoothly, thus causing high machining cost.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.